The information in this chapter only applies to release 8.1 and higher installations of Oracle. The term downgrading describes transforming an Oracle database into a previous release of the same version, such as transforming a database from release 8.1.7 to release 8.1.5. The term downgrading also describes transforming an Oracle database into a previous version, such as transforming a database from Oracle9i to Oracle7. This chapter describes downgrading to Oracle7 or release 8.0. If you want to downgrade to release 8.1 of Oracle, then see Chapter 13, "Downgrading to Release 8.1".

Some aspects of downgrading are operating system-specific. See your operating system-specific Oracle documentation for additional instructions about downgrading.

Downgrading from Oracle9i to Release 8.0

An Oracle9i database can be downgraded to a release 8.0 database. However, few downgrade paths are available, and the necessary procedures may require a great deal of time and effort. Also, it may not be possible to preserve data that uses new Oracle9i features that are not available with release 8.0.

The procedure for downgrading depends on whether the Oracle9i database contains new or changed data that must be preserved. Use the procedure that applies to your Oracle9i database:

Downgrading a Database That Does Not Contain New or Changed Data

If the Oracle9i database contains no new or changed data that must be preserved, then simply restore the complete backup of the previous release 8.0 source database and open it again. Make sure the restore includes the initialization parameters that were used in the previous release 8.0 database.

Use the release 8.0 Import utility to import the file previously exported from the Oracle9i database into the restored release 8.0 database.

Alternative Downgrading Methods

Using Export/Import to return data to a release 8.0 database is relatively simple if only a few tables have been updated using Oracle9i. However, copying an entire database of tables can be a long and complicated task; therefore, you should decide whether you need to return to release 8.0 before you update many tables using Oracle9i.

The following alternate method is available for downgrading an Oracle9i database to release 8.0:

Use your release 8.1 Oracle documentation to further downgrade the database to release 8.0.

See Also:

Oracle8i Migration for more information about downgrading from release 8.1 to release 8.0.

Downgrading from Oracle9i to Oracle7

An Oracle9i database can be downgraded to an Oracle7 database (such as release 7.3). However, few downgrade paths are available, and the necessary procedures may require a great deal of time and effort. Also, it may not be possible to preserve data that uses new Oracle9i features that are not available with Oracle7.

Oracle does not support downgrading from Oracle9i to Oracle7 using the Oracle9i Migration utility; in other words, the Oracle9i Migration utility does not support backward migration. Oracle9i provides no other facilities specifically for downgrading.

The procedure for downgrading depends on whether the Oracle9i database contains new or changed data that must be preserved. Use the procedure that applies to your Oracle9i database:

Downgrading a Database That Does Not Contain New or Changed Data

If the Oracle9i database contains no new or changed data that must be preserved, then simply restore the complete backup of the previous Oracle7 source database and open it again. Make sure the restore includes the initialization parameters that were used in the previous Oracle7 database.

Importing version 8 or Oracle9i materialized views into a version 7 database is not supported. You must recreate any materialized views in your version 7 environment.

Restore the complete backup of the previous Oracle7 database, and make sure the restore includes the previous initialization parameters.

See Also:

Oracle7 Server Administrator's Guide for more information about restoring a backed up Oracle7 database.

Open the restored Oracle7 database.

Use the Oracle7 Import utility to import the file previously exported from the Oracle9i database into the restored Oracle7 database.

Alternative Downgrading Methods

Several other methods are available for sending table data from the Oracle9i database back to the Oracle7 database. These methods of returning data to Oracle7 are relatively simple if only a few tables have been updated using Oracle9i. However, copying an entire database of tables can be a long and complicated task; therefore, you should decide whether you need to return to Oracle7 before you update many tables using Oracle9i.

The following alternate methods are available for downgrading an Oracle9i database to Oracle7:

Use SQL*Plus to create non-Oracle text files from the new Oracle9i data and then use SQL*Loader to load the data back into the Oracle7 database.

Use the SQL*Plus COPY command to copy the new data from the Oracle9i database tables into the tables in the earlier Oracle7 database.

If you are still running the earlier Oracle7 database, then re-create the table where data has been added or changed (using CREATE TABLE ... AS SELECT). Select the data in the Oracle9i database table through a distributed query from the Oracle7 database using a database link.